Episode 45 – Is Sugar Really That Bad for Health and Weight Loss?

Key Topics Covered

Sugar and body composition  

  • Sugar does not directly increase body fat more than other forms of carbohydrate.
  • Example: A study compared  4% vs 40% of calorie intake coming from sugar during a calorie deficit. The result showed similar outcomes for body composition for both groups.
  • At the end of the day, body composition is based off calories in vs calories out. Not the type of carbs consumed  
  • However, added sugars and processed food high in sugar can be easy to overconsume. 
    • Fibre, found in wholegrains is extremely filling and will likely cause someone to consume less calories than if all their carbs were coming from sugar.

Micronutrient intake  

  • Individuals are more likely to consume less micronutrients when added sugar intake is high.
  • Each calorie coming from added sugar is a calorie that could have been spent on food containing micronutrients.  

Added sugar vs natural sugar 

  • There’s no real difference between the two – sugar is sugar BUT added sugar doesn’t come alongside fibre and micronutrients. 
  • On that topic, fibre is consistently linked with positive health outcomes – which is another factor in this conversation. 
  • So obviously fruit which contains fibre and micronutrients is going to be “better” than lollies  
  • Many people market the “health benefits” of raw desserts (with dates, coconut, peanut butter, etc), however the literature shows that these desserts nutrition benefits are no greater than standard desserts.

Tooth decay  

  • Tooth decay is actually the main health issue consistently linked with sugar intake when all other variables are equal such as total calorie and macro intake.
  • Keeping in mind all other variables being equal is rare.
  • Sugar interacts with bacteria within plaque to produce acid that slowly dissolves tooth enamel. 
  • The World Health Organisation stronglu recommend that added sugar should be <10% of total calorie intake to help reduce tooth decay and overweight/obesity.
    • They have a conditional recommendation of <5% of total calories (this would be ~25g of added sugar max per day). 
Stage tooth decay infographic medical educational scheme names diagnosis vector flat illustration. Teeth formation steps, from healthy to deal, forming dental plaque caries in enamel, dentin and pulp


  • People often assume that high sugar intake is a major risk factor for diabetes, but it is more of an indirect risk factor than direct. 
  • Explained: A large population level study found that the risk of developing type 2 diabetes grew 1.1% per 150kcal of added sugar consumed per day over a 10 year period.
  • 150kcal = ~37g of added sugar.
  • Example: Consuming 4 x 150g = 600g of added sugar per day for a decade would line up as a 4.4% increase. 
  • So the linkage isn’t exactly strong there. 
  • Risk factors for T2DM are more likely to weight gain/being overweight. As this leads to insulin resistance which can be indirectly.

Cardiovascular disease  

  • Higher sugar intake is associated with coronary heart disease. 
  • A 2014 study found that “Over the course of the 15-year study, people who consumed 17% to 21% of their calories from added sugar had a 38% higher risk of dying from cardiovascular disease compared with those who consumed 8% of their calories as added sugar.” 
    • The author’s proposed mechanism was that sugar increased the risk of fatty liver, which increases the risk of diabetes, which increases the risk of heart disease.”
    • They also mentioned potential inflammation mechanisms which will discuss later. 
  • With fatty liver, it’s hard to pinpoint that to sugar. 80% of people who are in the obese class 1 category have fatty liver. 90% in the obese class 2 category have fatty liver. Fatty liver is far more strongly correlated with body fat levels than it is with sugar intake. While it is possible, it is rare for a lean individual with a relatively high sugar intake to have fatty liver. It just comes back to the same problem of higher sugar intake often leading to more calories and higher body fat levels anyway. 
  • However, a paper reviewing all the research up to 2013 highlighted that if calories were kept equal, replacing calories coming from other carb sources with sugar, up to 25% of total energy, in apparently healthy adults had no impact on cardiovascular disease. Obviously, things are different with health conditions though e.g. it would likely be different in somebody with diabetes 
heart disease: valve disease, aneurysm, coronary artery disease, cardiac arrhythmia, heart failture, cardiomyopathy and pericarditis


  • Similarly to other conditions, obesity increases the risk of cancer.  
  • Specifically, on the topic of sugar, the current consensus, quoting the National Health and Medical Research Council on the topic – “Upon reviewing all available evidence, consumption of sugar is not associated with an increased risk of cancer. There was sufficient evidence to conclude that there was no association between sugars and cancer of the pancreas, bowel, breast and bladder. There was no evidence of a direct association between sugar consumption and an increased risk of cancer of any type.”  
  • There is an argument that sugar “feeds” cancer cells.  
  • This is because cancer cells grow rapidly and use a great amount of glucose  
  • But it is not just sugar that turns into blood glucose. Carbs and protein can be broken down into glucose too. Technically fat can as well, although it is inefficient.  
  • So having a low sugar diet will not ‘starve’ cancer cells because glucose will be made from other forms of calories coming in  

Gut-health and Inflammation

  • Research has linked high intake of sugar with an increase in the relative abundance of Proteobacteria in the gut – which are typically considered bad, while simultaneously decreasing the abundance of Bacteroidetes – which are typically considered good. 
  • This linkage is considered to upset the balance of microbiota and also have increased pro-inflammatory properties. 
  • From a gut health perspective it is tough since we also know focusing on a wide variety of high fibre food does the opposite of this. 
  • Is it the increased sugar causing this? Or the lack of fibre in terms of quantity and variety? The research on this topic usually has high sugar intake, high saturated fat intake and low fibre (standard western diet) showing this outcome.  
  • I think whatever perspective you look at it from makes sense – increasing added sugar intake likely leads to this outcome in most cases whether it is direct or indirect. But I wouldn’t necessarily conclude that it is sugar for sure that causes the outcome. 


  • Consuming higher GI foods such as sugar is linked with acne. BUT it’s not a strong link and there are a bunch of other potential reasons for acne, but sugar is one option. 

Useful Links/ Resources

Studies Mentioned

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